Download MC7106 SIX CHANNEL POWER AMPLIFIER

MC7106
SIX CHANNEL
POWER
AMPLIFIER
MC7106
SIX CHANNEL
POWER
AMPLIFIER
1.
2.
3.
4.
IMPORTANT
SAFETY
INSTRUCTIONS
THESE
INSTRUCTIONS
ARE TO PROTECT
YOU AND THE
MclNTOSH
INSTRUMENT.
BE SURE TO
FAMILIARIZE
YOURSELF
WITH THEM
Read all instructions - Read the safety and operating instructions before operating the instrument.
Retain Instructions - Retain the safety and operating instructions for future reference.
Heed warnings - Adhere to warnings and operating instructions.
Follow Instructions - Follow all operating and use instructions.
WARNING: TO REDUCE RISK OF FIRE OR ELECTRICAL SHOCK, DO NOT EXPOSE THIS INSTRUMENT TO RAIN OR MOISTURE.
5. Power Sources - Connect the power supply only to the type described in the operating instructions
or as marked on the unit.
6. Power-Cord Protection - Route power-supply cords so that they are not likely to be walked on or
pinched by items placed upon or against them, paying particular attention to cords at plugs,
convenience receptacles, and the point where they exit from the instrument.
7. Ventilation - Locate the instrument for proper ventilation. For example, the instrument should not
be placed on a bed, sofa, rug, or similar surface that may block ventilation openings; or, placed
in a built-in installation, such as a bookcase or cabinet, that may impede the flow of air through
the ventilation openings.
8. Heat - Locate the instrument away from heat sources such as radiators, heat registers, stoves, or
other appliance (including amplifiers) that produce heat.
9. Wall or Cabinet Mounting - Mount the instrument in a wall or cabinet only as described in the owner's
manual.
10. Water and Moisture - Do not use the instrument near water - for example, near a bathtub, washbowl,
kitchen sink, laundry tub, in a wet basement, or near a swimming pool, etc.
11. Cleaning - Clean the instrument by dusting with a dry cloth. Clean the panel with a cloth moistened
with a window cleaner.
12. Object and Liquid Entry - Do not permit objects to fall and liquids to spill into the instrument through
enclosure openings.
13. Nonuse Periods - Unplug the power cord from the AC power outlet when left unused for a long period
of time.
14. Damage Requiring Service Service must be performed by qualified service personnel when:
A. The power supply cord or the plug has been damaged; or
B. Objects have fallen, or liquid has been spilled into the instrument; or
C. The instrument has been exposed to rain; or
D. The instrument does not appear to operate normally or exhibits a marked change in performance;
or
E. The instrument has been dropped, or the enclosure damaged.
15. Servicing - Do not attempt to service beyond that described in the operating instructions. All other
service should be referred to qualified service personnel.
16. Grounding or Polarization - Do not defeat the inherent design features of the polarized plug. Nonpolarized line cord adaptors will defeat the safety provided by the polarized AC plug.
17. CAUTION: TO PREVENT ELECTRICAL SHOCK DO NOT USE THIS (POLARIZED) PLUG
WITH AN EXTENSION CORD, RECEPTACLE OR OTHER OUTLET UNLESS THE BLADES CAN
BE FULLY INSERTED TO PREVENT BLADE EXPOSURE.
ATTENTION: POUR PREVENIR LES CHOCS ELECTRIQUES PAS UTILISER CETTE
FICHE POLARISEE AVEC UN PROLONGATEUR, UNE PRISE DE COURANT OU UNE AUTRE
SORTIE DE COURANT, SAUF SI LES LAMES PEUVENT ETRE INSEREES A FOND SANS EN
LAiSSER AUCUNE PARTIE A DECOUVERT.
The lightning flash with arrowhead, within an equilateral triangle, is intended to alert the
user to the presence of uninsulated "dangerous voltage" within the product's enclosure
that may be of sufficient magnitude to constitute a risk of electric shock to persons.
CAUTION
CAUTION: TO PREVENT THE RISK OF ELECTRIC SHOCK, DO NOT
RISK OF ELECTRIC SHOCK
DO NOT OPEN
REMOVE COVER (OR BACK). NO USER-SERVICABLE PARTS INSIDE.
REFER SERVICING TO QUALIFIED PERSONNEL.
The exclamation point within an equilateral triangle is intended to alert the user to the
presence of important operating and maintenance (servicing) instructions in the literature
accompanying the appliance.
Copyright 1993 © by
Mclntosh Laboratory Inc.
WARNING: THIS UNIT IS CAPABLE OF PRODUCING HIGH SOUND
PRESSURE LEVELS. CONTINUED EXPOSURE TO HIGH SOUND
PRESSURE LEVELS CAN CAUSE PERMANENT HEARING IMPAIRMENT
OR LOSS. USER CAUTION IS ADVISED AND EAR PROTECTION IS
RECOMMENDED WHEN PLAYING AT HIGH VOLUMES.
2
Your decision to own this piece of Mclntosh Stereo Equipment ranks you at the very top
among discriminating music listeners. You now have "The Best". The Mclntosh dedication
to "Quality", is assurance that you will receive thousands of hours of musical enjoyment from
this unit.
Please take a short time to read the information in this manual. We want you to be as familiar
as possible with all the features and functions of your new piece of Mclntosh. This will ensure that you receive all the performance benefits this instrument can offer you, and that
it will become a highly valued part of your home music system.
THANK
YOU
The serial number, purchase date, and Mclntosh Laboratory Service Contract number are
important to you for possible insurance claim or future service. Record this information here.
Serial Number
Purchase Date
Service Contract Number
Upon application, Mclntosh Laboratory provides a Service Contract to the original purchaser.
Your Mclntosh Authorized Service Agency can expedite repairs when you provide the Service Contract with the instrument for repair.
SERVICE CONTRACT
4
INTRODUCTION
. 5
HOW TO INSTALL THE MC7106
. 5
CUSTOM INSTALLATION DIAGRAM
MC7106 OPERATING CONFIGURATIONS
REAR PANEL FEATURES AND CONNECTIONS
AMPLIFIER/SPEAKER CONFIGURATIONS
MclNTOSH HOME THEATER AMPLIFIER/SPEAKER CONNECTIONS
SPECIFICATIONS
TECHNICAL DESCRIPTION
.6
.7
7, 8, 9
.9,10,11
12, 13
14
15, 16
3
TABLE OF
CONTENTS
TAKE ADVANTAGE OF 3 YEARS OF CONTRACT SERVICE. . .
FILL IN THE APPLICATION NOW.
Your MC7106 Power Amplifier will give you many years of satisfactory performance. If you
have any questions, please contact,
Mclntosh Laboratory Inc.
2 Chambers Street
Binghamton, New York 13903-2699
Phone: 607-723-3512
MclNTOSH
THREE YEAR
SERVICE
CONTRACT
An application for A THREE YEAR SERVICE CONTRACT is included with this manual.
The terms of the contract are:
1. If the instrument covered by this contract becomes defective, Mclntosh will provide all parts,
materials, and labor needed to return the measured performance of the instrument to the
original performance limits free of any charge. The service contract does not cover any
shipping costs to and from the authorized service agency or the factory.
2. Any Mclntosh authorized service agency will repair all Mclntosh instruments at normal
service rates. To receive the free service under the terms of the service contract, the service contract certificate must accompany the instrument when taken to the service agency.
3. Always have service done by a Mclntosh authorized service agency. If the instrument is
modified or damaged as a result of unauthorized repair the service contract will be cancelled. Damage by improper use or mishandling is not covered by the service contract.
4. The service contract is issued to you as the original purchaser. To protect you from
misrepresentation this contract cannot be transferred to a second owner.
5. Units in operation outside the United States and Canada are not covered by the Mclntosh
Factory Service Contract, irrespective of the place of purchase. Nor are units acquired
outside the USA and Canada, the purchasers of which should consult with their dealer
to ascertain what, if any, service contract or warranty may be available locally.
A
Mclntosh Laboratory has earned a world wide reputation for its technical contributions to
improved sound reproduction. The technical innovations in Mclntosh products have integrity
proven by time. The Mclntosh "Classic" design is recognized as the most outstanding in the
industry.
Mclntosh products are designed to be maximum user friendly so anyone can enjoy using
them. They are also designed for easy maintenance. The legendary reliability of Mclntosh
products has been a matter of record since 1949.
The MC7106, Six Channel Power Amplifier, is ideal for a "Mclntosh Quality" Home Theater
system. It can also be used in systems where multi amplifiers are needed for remote zones.
All three pairs of stereo channels can be switched into Bridged configuration for 320 watts
each. You have a choice of six 100 watt channels, (160 watts into 4 ohms), four 100/160 watt
channels and one 320 watt channel, two 100/160 watt channels and two 320 watt channels
or three 320 watt channels. The MC7106 configuration is perfect for a home theater system
that will reproduce Dolby Surround TM soundtracks. The MC7106 has been Home
THX® Audio licensed by Lucasfilm Ltd. to meet all the specialized THX requirements for
reproducing Dolby Surround movie soundtracks. The MC7106 includes a rear panel 25 pin
connector for a computer type cable to accept all six audio channels and AC power control
information from a Mclntosh C39 or MX 130 Audio/Video Control Center. The C39 and MX 130
include built-in Dolby Pro Logic™ decoding circuits, and can be converted to Home
THX® Audio with the add-on Mclntosh THX-M module. The Home THX® Audio System is a
licensing program of Lucasfilm Ltd. which defines new technologies and quality standards
for accuracy in home theaters.
Each of the six MC7106 direct coupled channels can deliver a Peak Output Current of 25
amperes, making it compatible with a wide variety of loudspeakers. All six channels incorporate the Mclntosh POWER GUARD circuit which prevents output clipping with its harsh
and damaging distortion.
There are front panel LED electronic power level indicators for all six channels which accurately read the percentage of maximum power output. The top LED for each channel display
lights whenever the Power Guard circuit is activated. This indicates that the amplifier is being protected from overdrive and clipping. The output level where Power Guard acts will be
well above the rated power due to conservative Mclntosh design philosophy.
The LED power level displays will automatically dim as the room lights dim. A rear panel
control allows you to adjust the LED illumination intensities when they are dimmed, or turn
them off completely. The front panel is "Classic Mclntosh", all glass, with lighted nomenclature.
THX® is a registered trademark of Lucasfilm Ltd.
DOLBY SURROUND, PRO LOGIC and the Double "D" Symbol are registered trademarks
of Dolby Laboratories Licensing Corporation,
The MC7106 can be placed upright on a table or shelf, standing on its four plastic feet.
The amplifier can also be custom installed in a cabinet of your choice. The mounting panel
cutout and amplifier dimensions are shown in the diagrams found on Page 6 of this manual.
Always provide adequate ventilation for the amplifier. The trouble free life of any electronic
instrument is greatly extended by providing sufficient ventilation for proper cooling.
Allow at least 1-1/2 inches (3.8cm) above the heat sink area to allow the free flow of air.
The recommended minimum depth for mounting, including clearance for connectors, is 20
inches (51cm) behind the front mounting panel. Clearance required in front of the mounting
panel surface is 1 inch (2.54cm).
5
INTRODUCTION
HOW TO INSTALL
THE MC7106
CUSTOM
INSTALLATION
DIAGRAM
6
The versatile Mclntosh MC7106 can be used in four different basic operating configurations.
1.
2.
3.
4.
Six separate 100 watt channels into 8 ohms, (160 watts into 4 ohms).
Four 100/160 waft channels and one 320 watt channel, bridged (8 ohms).
Two 100/160 watt channels and two 320 watt channels, bridged (8 ohms).
Three 320 watt channels, bridged (8 ohms).
MC7106
OPERATING
CONFIGURATIONS
The Mclntosh HT, Home Theater Series loudspeakers are 4 ohm impedance. The Mclntosh
MC7106 will deliver a total of 960 watts of power into these six loudspeakers when used in
a Mclntosh Home Theater System.
The MC7106 is designed to directly interface with a Mclntosh C39 or MX130 Audio/Video
Control Center. The connection is through a shielded 25 conductor Subminiature "D" computer type cable connected from the Mclntosh Control Center to the THX INPUT connector
on the MC7106 rear panel. All six program signals as well as AC power control signals are
sent to the amplifier through this cable. Individual discrete cables can also be used if desired.
The MC7106 also is an ideal amplifier for applications requiring multi zone amplifiers. For
example, the MC7106 can supply power to a pair of speakers in three separate areas when
it is used with the Mclntosh CR10 Remote Control System.
Use high quality input and output connecting cables. Proper cables will ensure receiving
the best possible performance from your Mclntosh system. Your Mclntosh dealer can advise
you on the types and lengths of cables that will work best in your installation.
Refer to the hookup drawings for information on how to connect the inputs and outputs for
each installation configuration. Pay special attention to the polarities of the speaker hookups.
The top RED speaker output terminals are positive, and the bottom BLACK terminals are
negative or common. This configuration applies when the amplifier channels are used
individually.
In BRIDGED configuration, only the Top RED terminals are used. Follow the plus and minus
polarity indications marked above the RED terminals. When using a pair of channels in BRIDGED mode, set the rear panel MODE Switch for that pair of channels to the BRIDGED position.
Use only speakers with an impedance of 8 ohms or higher with BRIDGED channels.
Refer to the numbers on the rear panel drawing for the descriptions of the MC7106 connections and controls.
1. POWER (ON, OFF/REMOTE)
ON position turns the MC7106 AC power on. OFF/REMOTE allows the MC7106 AC power
to be turned on by a control signal from a Mclntosh Control Center through the 25 conductor
THX connector. The amplifier can also be turned on by a control signal fed from a Mclntosh
Control Center POWER CONTROL Output to the MC7106 rear panel POWER CONTROL IN
connector.
2. MODE (NORMAL/BRIDGED)
Set this switch to NORMAL when channels 5 and 6 are being used separately. Set the switch
to BRIDGED when the two channels are connected together for bridged operation.
3. INPUTS 5 and 6
Connect cables from a preamplifier, control center or other accessory output- to these
inputs.
7
REAR PANEL
FEATURES
AND
CONNECTIONS
REAR PANEL
FEATURES
AND
CONNECTIONS
4. LEVEL 5 and 6
Set the controls fully clockwise to the THX (1 volt) reference position when using the amplifier
with a Mclntosh C39 or MX130 Control Center adapted for the Home THX® Audio System.
For use with other audio systems, set the controls as desired.
5. DISPLAY BRIGHTNESS (MAX/OFF)
(Flush mounted screwdriver control)
Adjust this control for the desired brightness of the front panel power level LED displays
when the room is darkened. When the room lighting returns to normal, the displays will also
return to their normal intensity. Turn the control fully counterclockwise to turn the displays
completely off. The front panel teal nomenclature retains normal illumination at all times.
6. MODE (NORMAL/BRIDGED)
Set this switch to NORMAL when channels 3 and 4 are being used separately. Set the switch
to BRIDGED when the two channels are connected together for bridged operation.
7. INPUTS 3 and 4
Connect cables from a preamplifier, control center or other accessory outputs to these
inputs.
8. LEVEL 3 and 4
Set the controls fully clockwise to the THX (1 volt) reference position when using the amplifier
with a Mclntosh C39 or MX130 Control Center adapted for the Home THX® Audio System.
For use with other audio systems, set the controls as desired.
9. THX® INPUT
Connect a shielded 25 conductor Subminiature "D" male-to-female computer type cable
from the 6 channel output connector on a Mclntosh C39 or MX130 to the MC7106 THX® input
connector. This cable will supply all six output signals from the Control Center for surround
sound operation. It also supplies the control signal to turn the MC7106 AC power on and off.
10. MODE (NORMAL/BRIDGED)
Set this switch to NORMAL when channels 1 and 2 are being used separately. Set the switch
to BRIDGED when the two channels are connected together for bridged operation.
11. INPUTS 1 and 2
Connect cables from a preamplifier, Control Center or other accessory outputs to these
inputs.
12. LEVELS 1 and 2
Set the controls fully clockwise to the THX (1 volt) reference position when using the amplifier
with a Mclntosh C39 or MX130 Control Center adapted for the Home THX® Audio System.
For use with other audio systems, set the controls as desired.
13. OUTPUTS 1 and 2, and BRIDGED OUTPUT
For separate channel operation, connect the Hot lead of a loudspeaker to the + (Plus)
RED upper terminal, and the Common lead to the - (Minus) BLACK lower terminal of each
channel.
For BRIDGED operation, connect the Hot lead of a loudspeaker to the + (Plus) RED upper
Channel 1, BRIDGED terminal, and the Common lead to the - (Minus) RED upper Channel
2, BRIDGED terminal.
8
14. OUTPUTS 3 and 4, and BRIDGED OUTPUT
For separate channel operation, connect the Hot lead of a loudspeaker to the + (Plus)
RED upper terminal, and the Common lead to the - (Minus) BLACK lower terminal of each
channel.
For BRIDGED operation, connect the Hot lead of a loudspeaker to the + (Plus) RED upper
REAR PANEL
FEATURES
AND
CONNECTIONS
Channel 3, BRIDGED terminal, and the Common lead to the - Minus) RED upper Channel
4, BRIDGED terminal.
15. POWER CONTROL, IN/OUT
The MC7106 AC power can be turned on and off by a control signal fed to the POWER
CONTROL IN connector. This signal is available from a Mclntosh C39 or MX130 Control Center
through the 25 conductor computer type cable, or directly from a Control Center POWER CONTROL Output. The MC7106 POWER CONTROL OUT jack will feed the same AC power control signal out to another accessory component with a compatible Power Control input- The
POWER CONTROL connectors are standard 1/8 inch mini phone plugs. Only the tip and sleeve
are used for connections.
The MC7106 POWER switch must be in the OFF/REMOTE setting for the power control
signals to properly operate the MC7106 AC power.
16. OUTPUTS 5 and 6, and BRIDGED OUTPUT
For separate channel operation, connect the Hot lead of a loudspeaker to the + (Plus)
RED upper terminal, and the Common lead to the - (Minus) BLACK lower terminal of each
channel.
For BRIDGED operation, connect the Hot lead of a loudspeaker to the + (Plus) RED upper
Channel 5, BRIDGED terminal, and the Common lead to the - (Minus) RED upper Channel
6, BRIDGED terminal.
17. AC POWER CORD
Connect the MC7106 to a live 50/60Hz, 120 volt AC wall outlet. Do not connect the unit
to an AC outlet on the rear panel of a Preamplifier or Control Center.
18. 15A 250V (Fuse)
CAUTION: For continued protection against fire hazard, replace only with the same type
15A-250V SLO BLO fuse.
The following hookup diagrams show how to connect the six channels of the MC7106 in
four different output configurations. The MC7106 has excellent channel separation, so the
six channels can be used as six separate amplifiers, in mono or stereo, each with its dedicated
input signal and speaker output. Any of the following operating configurations can be used
for multi zone amplifier requirements.
9
AMPLIFIER/
SPEAKER
CONFIGURATIONS
SIX 100/160
WATT
CHANNELS
SPEAKER
6
100 WATTS
SPEAKER
5
100 WATTS
SPEAKER
4
100 WATTS
SPEAKER
3
100 WATTS
SPEAKER
2
100 WATTS
SPEAKER
1
100 WATTS
FOUR 100/160
WATT
CHANNELS
AND
ONE 320 WATT
CHANNEL,
BRIDGED
SPEAKER
6
100 WATTS
10
SPEAKER
5
100 WATTS
SPEAKER
4
100 WATTS
SPEAKER
3
100 WATTS
SPEAKER
1
300 WATTS
CHANNELS 1 AND 2 BRIDGED
TWO 100/160
WATT CHANNELS
AND
TWO 320 WATT
CHANNELS,
BRIDGED
SPEAKER
6
100 WATTS
SPEAKER
5
100 WATTS
SPEAKER
3
300 WATTS
SPEAKER
2
300 WATTS
CHANNELS 3 AND 4 BRIDGED
SPEAKER
2
300 WATTS
CHANNELS 1 AND 2, 3 AND 4, 5 AND 6 BRIDGED
SPEAKER
1
300 WATTS
CHANNELS 1 AND 2 BRIDGED
SPEAKER
1
300 WATTS
11
THREE 320 WATT
CHANNELS,
BRIDGED
MclNTOSH
HOME THEATER
AMPLIFIER/
SPEAKER
CONNECTIONS
HOME THEATER SURROUND, USING SIX 100/160 WATT CHANNELS WITH A
MclNTOSH C39 OR MX130 AUDIO/VIDEO CONTROL CENTER
The Mclntosh HT, Home Theater Series loudspeakers are 4 ohm impedance. The Mclntosh MC7106 will deliver a total of 960 watts of power into these six loudspeakers when used
in a Mclntosh Home Theater System.
Program signals coming from a Mclntosh C39 or MX 130 Control Center will be fed to the
MC7106 inputs through the rear panel 25 pin THX INPUT connector. All six channels will
receive signals when the Control Centers are used in the HALL, CINEMA 1, (Dolby Pro Logic)
or CINEMA 2, (THX®Audio), MODES. AC power control for the MC7106 is also fed through
the 25 pin connector. The MC7106 AC power cable must be connected to a live AC wall outlet
at all times. Set the MC7106 rear panel POWER switch to the OFF/REMOTE position.
Do not connect the MC7106 power cable to a Control Center rear panel AC outlet.
The six separate Control Center rear panel RCA output jacks may also be used to connect
to the MC7106 inputs instead of the 25 conductor cable. In this mode of connecting, to control the MC7106 AC power you also must connect a cable from the Control Center POWER
CONTROL jack to the MC7106 POWER CONTROL IN jack. Connect the MC7106 power cable
to a live AC wall outlet and set the POWER switch to the OFF/REMOTE position.
OUTPUT CHANNEL ASSIGNMENT USING THE THX 25 PIN CONNECTOR
A Mclntosh C39 or MX130 used in the HALL, CINEMA 1, or CINEMA 2 Mode will feed
the following surround sound signals to the six channels of the MC7106 through the 25 conductor THX connector.
CHANNEL 1: Center Front
CHANNEL 4: Right Front
CHANNEL 2: Left Surround
CHANNEL 5: Subwoofer
CHANNEL 3: Left Front
CHANNEL 6: Right Surround
For further information on other operating modes of the C39 or MX 130, consult the
applicable owner's manual.
12
MclNTOSH
HOME THEATER
WITH SIX
160 WATT
CHANNELS
13
SPECIFICATIONS
PERFORMANCE LIMITS
Performance limits are the maximum
deviation from perfection permitted for a
Mclntosh instrument. We promise you that
when you purchase an MC7106 from a
Mclntosh franchised dealer, it will be
capable of performance at or better than
these limits.
POWER OUTPUT, SIX CHANNELS
100 watts per channel into 8 ohm loads,
or 160 watts per channel into 4 ohm loads
minimum sine wave continuous average
power output per channel, all channels
operating.
The output RMS voltage is:
28.3V across 8 ohms
25.2V across 4 ohms
POWER OUTPUT,
TWO CHANNELS BRIDGED
320 watts into an 8 ohm load, minimum
sine wave continuous average power output.
The output RMS voltage is:
50.6V across 8 ohms
OUTPUT LOAD IMPEDANCE
8 or 4 ohms, for all six separate channels
8 ohrns, Bridged operation
RATED POWER BAND
20Hz to 20,000Hz
TOTAL HARMONIC DISTORTION
0.005% maximum harmonic distortion at
any power level from 250 mW to rated power
output.
IHF DYNAMIC HEADROOM
8 ohms, 1.8dB
4 ohms, 2.1dB
FREQUENCY RESPONSE
+ 0, -0.25dB from 20Hz to 20,000Hz
+ 0, -3.0dB from 10Hz to 100,000Hz
INPUT SENSITIVITY
1V, (2.5V with Level control at center
detent)
14
A-WEIGHTED SIGNAL-TO-NOISE RATIO
93dB (113dB below rated output)
INTERMODULATION DISTORTION, SMPTE
0.005% maximum if instantaneous peak
power does not exceed twice the output
power rating.
RATINGS
WIDE BAND DAMPING FACTOR
200 at 8 ohms
100 at 4 ohms
INPUT IMPEDANCE
20,000 ohms
POWER GUARD
Clipping is prevented and THD does not
exceed 2% with up to 14dB overdrive at
1000Hz.
POWER REQUIREMENTS
120V, 50/60Hz, 12A UL/CSA
MECHANICAL
SIZE
Front panel: 17 1/2 inches (44.5cm) wide,
by 7 1/8 inches (18.1cm) high. Depth behind
the front mounting panel is 20 inches
(50.8cm) including clearance for connectors.
Panel clearance required in front of mounting panel is 1 inch (2.54cm).
FINISH
Front panel is glass with gold/teal
nomenclature illumination. Chassis and
chassis cover are black.
WEIGHT
52 pounds (23.6Kg) net, 70 pounds
(31.8Kg) in shipping carton.
DESIGN PHILOSOPHY
The MC7106 Six Channel power amplifier is designed to operate loudspeakers with a
nominal impedance of 4 to 8 ohms. It features a new circuit design that keeps distortion levels
so low it takes special test gear for accurate measurements.
The design philosophy incorporated in this outstanding amplifier involved many different
techniques, all based on sound scientific logic. Every stage of voltage or current amplification was designed to be as linear as possible. Negative feedback is then utilized to enhance
the performance. Mclntosh engineers know how to properly design negative feedback circuits
so they contribute to the extremely low distortion performance expected from a Mclntosh
amplifier. All transistors are selected to have nearly constant current gain (Beta) over the entire current range they must cover. Output transistors in particular, have matched uniform
current gain, high current-bandwidth product and large active region safe operating area.
Resistors and capacitors in the signal path are carefully selected to have exceedingly low
voltage coefficients, (change of resistance or reactance with applied voltage). Precision metal
film resistors, low dielectric absorption film capacitors and premium audio grade electrolytics
are used in all critical circuit locations.
PROTECTION CIRCUITS
Some manufacturers claim that their products do not need or use protection circuits and
that such circuits compromise performance. Mclntosh feels that protection circuits are
desirable and necessary to prevent amplifier or loudspeaker damage due to abnormal circumstances. The genius of Mclntosh engineering has resulted in protection circuits which
have no effect or compromise on the normal performance of a power amplifier. The SENTRY
MONITOR circuit is a good example. The MC7106 incorporates six specific protection circuits to enhance its performance, increase its reliability and protect loudspeakers.
SENTRY MONITOR CIRCUIT
All power transistors have limits for the maximum amount of power they can handle. The
MC7106 output transistors and power supply have been designed to allow very high current
flow into properly matched load impedances. However, if a short circuit or very low load impedance is connected to any of the MC7106 outputs, destructive current levels could be reached if it was not controlled by the SENTRY MONITOR circuit- This circuit senses the dynamic
operating time, voltage and current of the output stage, and controls it to safe operating limits.
There is absolutely no compromise in sonic performance and it ensures safe operation
of the amplifier under even the most extreme operating conditions.
THERMAL CONTROL
All power transistors have limits for the maximum amount of heat they can safely tolerate.
The MC7106 uses highly efficient amplifying circuits which produce relatively little heat for
the output power produced. The amplifier uses large area heat sinks to efficiently dissipate
what heat it does generate. Natural convection air flow is sufficient for safe cool operation.
If the cooling air is blocked, or the amplifier operating temperature is forced too high, thermal cutout switches will turn off the speakers on one or more pairs of channels. Both POWER
GUARD indicators will light continuously for the channels that are affected to show that thermal protection is operating. When the problem is corrected and the amplifier cools down to
its normal operating temperature, the speakers will be turned back on.
15
TECHNICAL
DESCRIPTION
TECHNICAL
DESCRIPTION
DIRECT CURRENT FAILURE PROTECTION
A protection circuit is provided that turns off the speakers if for any reason a DC voltage
should appear at the output terminals of any one of the six channels. The speakers will turn
off only for the pair of channels that are affected. This safeguard prevents possible speaker
damage.
POWER GUARD*
The MC7106 amplifier includes the unique patented Mclntosh POWER GUARD circuit.
POWER GUARD eliminates the possibility of ever overdriving the amplifier into clipping.
Clipping occurs when an amplifier is overdriven past its output design capabilities. An overdriven amplifier can produce both audible and ultrasonic distortion levels approaching 40%.
The audible distortion is unpleasant to hear, but the ultrasonic distortion is also undesirable,
since it can damage tweeter loudspeakers.
The POWER GUARD circuit acts as a waveform comparator, monitoring both the input and
output waveforms. Under normal operating conditions there are no differences between these
waveforms. If an amplifier channel is overdriven beyond its maximum distortion free output,
there will be a difference between the two signal waveforms. When the difference exceeds
0.3% (equivalent to 0.3% harmonic distortion), the amber POWER GUARD indicator will light.
If the difference continues to increase, the POWER GUARD circuit will control an electronic
attenuator at the amplifier channel input to reduce the gain just enough to prevent any further increase in distortion. Distortion will not exceed 2% with as much as 14dB overdrive
at 1000Hz.
A Mclntosh power amplifier with POWER GUARD will always deliver its maximum distortion free output. This power is always well above its rated power due to the Mclntosh philosophy
of conservative design. You will never experience the harsh and damaging distortion due to
clipping when using a Mclntosh amplifier with POWER GUARD.
POWER GUARD is protected by U.S. Patent No. 4048573.
16
The letters and numbers correspond to the paragraphs on pages 7, 8, and 9.
04010100
BE022003